Theoretical Study of the Structure and Reactivity of Ylides of N, P, As, Sb, and Bi

Naito, Takashi; Nagase, Shigeru; Yamataka, Hiroshi

doi:10.1021/ja00101a029

Cited by 80 publications

(98 citation statements)

References 2 publications

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“…Part of the problem is the lack of information concerning the nature of the transition states or transient intermediates that might be present in the Wittig reaction. Several theoretical studies have been undertaken in order to provide an insight on this matter [10][11][12][13][14][15][16][17][18]. For the most part, these studies make use of the mythical Wittig reaction [10,11,[13][14][15]18] (the reaction of methylidenephosphorane with formaldehyde) to model this olefination process.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the mechanism of the Wittig reaction: Ab initio and MNDO-PM3 treatment of the reaction of unstabilized, semistabilized, and stabilized ylides with acetaldehyde

et al. 1997

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Section: Introductionmentioning

confidence: 99%

Theoretical study of the mechanism of the Wittig reaction: Ab initio and MNDO-PM3 treatment of the reaction of unstabilized, semistabilized, and stabilized ylides with acetaldehyde

et al. 1997

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“…The smaller energy barrier and the exothermic reaction heat in the former reaction indicate a higher reactivity between two Si 4 O 2 clusters than between two Si 3 O 3 clusters. 22 The significant difference in reaction energetics would ensure that the relative reactivity of Si 4 O 2 clusters would remain higher than the Si 3 O 3 clusters even at higher temperatures. On the other hand, there is no binding found between Si 2 O 4 clusters, indicating an unfavorable bond formation.…”

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confidence: 99%

High reactivity of silicon suboxide clusters

et al. 2001

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The recent silicon-oxide-assisted formation of Si nanostructures has been studied based on quantummechanical calculations of Si n O m (n,mϭ1 -8) clusters. We found that ͑1͒ energetically the most favorable small silicon-oxide clusters have O atomic ratios at around 0.6, and ͑2͒ remarkably high reactivity at the Si atoms exists in silicon suboxide Si n O m clusters with 2nϾm. The results show that the formation of Si-Si bonds is preferred and thus facilitates the nucleation of Si nanostructures when silicon suboxide clusters come together or stack to a substrate. DOI: 10.1103/PhysRevB.64.113304 PACS number͑s͒: 61.46.ϩw, 73.22.Ϫf Silicon oxide has found important applications in wide fields such as microelectronics, optical communications, and thin-film technology. 1-3 Recent work 4 further showed that silicon oxide could also play an important role in the fabrication of an important nanometer material, the Si nanowire, 5,6 which has attracted much attention for its interesting quantum confinement effect as well as useful electrical, optical, mechanical, and chemical properties. The formation of Si nanowires was achieved by using Si powder sources mixed with SiO 2 . 4 A high yield of nanowires has been obtained when the chemical compositions of Si and O in the source are approximately equal. 7 On the contrary, the important role of oxide is not needed in the conventional growth mechanisms of nanowires. 8,9 To understand the oxide-assisted formation mechanism, the exploration of silicon oxide clusters about their geometric, electronic, and chemical properties would provide useful information.To promote various technological applications based on silicon oxide, theoretical investigations have been performed on small silicon oxide clusters. Systems, such as isolated SiO 2 , gas-phase oligomers (SiO 2 ) n ͑nр8, nϭ18͒, 10 Si(SiO 2 ) n (nϭ2,3), (SiO 2 ) n (nϭ1 -4), (SiO 2 ) n (n ϭ3 -5), 11 Si 3 O m (mϭ1 -6), 12 Si 2 O 4 2Ϫ , Si 2 O 5 2Ϫ , 13 charged and neutral Si n O m ͑nр6, mр12͒, 14 and (SiO) n (nр5), 15 have been studied using ab initio theories. Information achieved includes geometric structures, energetics, bonding, energy gaps, and valence electronic structures of these species. However, understanding of the oxide-assisted formation of Si nanowires in which silicon oxide acts as a special ''catalyst'' would require a systematic study of Si n O m . In this work, we have made such a systematic study of Si n O m (n,mϭ1 -8) at the quantum-mechanical level, aiming at elucidating the oxide-assisted formation mechanism of silicon nanowires.Energetically, the more favorable structure has been searched for each composition of Si n O m (n,mϭ1 -8) by means of calculations with density functional theory ͑DFT͒. The DFT calculations in this work used the popular B3LYP method, which is based on the Becke-type three-parameter density functional theory. 16 An economic basis set, where 3-21G and 6-31G* were selected to describe Si and O, respectively, according to their electronegativities and charge transfers, 17 was used in ...

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“…Besides the numbering of atoms, in Figure 3 one can see that the phosphorus atom (P2) is placed in the center of a distorted trigonal bipyramid. This type of geometry is obtained from experimental data 2, 19, 41–45 as well as through ab initio calculations 21, 32, 46–49. The equatorial vertices of the bipyramid are formed of three carbon atoms: C3 atom at which the propyl chain is bound and C14 and C20 atoms belonging to two phenylic rings.…”

Section: Methodsmentioning

confidence: 99%

New possible ionic structures in Wittig reaction: Analysis of stability and rotation barriers by semiempirical PM3 method

Pascariu¹,

Berger²,

Mracec³

2007

Int J of Quantum Chemistry

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ABSTRACT:For the Wittig reaction between butylidentriphenylphosphorane and benzaldehyde studied previously using NMR spectroscopy, three ionic intermediates have been proposed in order to explain the "stereochemical drift" (different ratio in oxaphosphetane stereoisomers compared with the ratio of the final Z/E olefins). In this paper, the PM3 semiempirical MO method was applied on the proposed ionic intermediates. Two of the ionic intermediates could lead to a shift of the reaction towards the final products, olefins and phosphine oxide, while the third intermediate could be implicated in a retro-Wittig reaction.

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Theoretical Study of the Structure and Reactivity of Ylides of N, P, As, Sb, and Bi

Cited by 80 publications

References 2 publications

Theoretical study of the mechanism of the Wittig reaction: Ab initio and MNDO-PM3 treatment of the reaction of unstabilized, semistabilized, and stabilized ylides with acetaldehyde

Theoretical study of the mechanism of the Wittig reaction: Ab initio and MNDO-PM3 treatment of the reaction of unstabilized, semistabilized, and stabilized ylides with acetaldehyde

High reactivity of silicon suboxide clusters

New possible ionic structures in Wittig reaction: Analysis of stability and rotation barriers by semiempirical PM3 method

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